ifdef out a variable used only on Windows.

Also, fix identation - tab stops are set every 8 spaces, not every 4
spaces, in UN*X, which is why the mode lines specify that.

Change-Id: If7cfc2cdae26feb2d5c13e31a32ed950354fb15b
Reviewed-on: https://code.wireshark.org/review/16789
Reviewed-by: Guy Harris <guy@alum.mit.edu>

epan/wmem/wmem_test.c

@@ -480,7 +480,9 @@ wmem_test_stringperf(void)
 {
 #define LOOP_COUNT (1 * 1000 * 1000)
     wmem_allocator_t   *allocator;
-	char                buffer[1];
+#ifdef _WIN32
+    char                buffer[1];
+#endif
     char               **str_ptr = g_new(char *, LOOP_COUNT);
     char               *s_val = "test string";
     double              d_val = 1000.2;